Department of Oral Medicine and Pathology, University of Pittsburgh, Pittsburgh PA, USA

(a6)

Center for Neural Science, New York University, New York, NY, USA

Published online: 01 January 2001

Abstract

It is currently thought that New World monkeys, prosimians, and humans are the only primates to possess
vomeronasal organs (VNOs) as adults. Recent studies of the human VNO suggest that previous
investigations on Old World primates may have missed the VNO. We examined nasal septa from the
chimpanzee (Pan troglodytes) grossly and histologically for comparison with nasal septa from humans, Old
World monkeys (Macaca fascicularis, M. nemistrina) and prosimian primates
(Microcebus murinus, Otolemur garnettii). Grossly, chimpanzees had depressions on the nasal septum similar to fossae reported anterior to
the VNO openings in humans. Histologically, chimpanzees and humans had bilateral epithelial tubes which
were above the superior margin of the paraseptal cartilages (vomeronasal cartilage homologue). The
epithelial tubes had a homogeneous ciliated epithelium. These structures were thus positionally and
structurally identical to the human VNO and unlike the well-developed prosimian VNOs which were
surrounded by vomeronasal cartilage. Macaques had no structures which resembled the VNO of either the
prosimians or humans. The results demonstrate that the VNO is present postnatally in the chimpanzee and
is almost identical to the human VNO in its anatomical position and histological structure. This in turn
suggests that the reported absence of the VNO in at least some adult Old World primates is artifactual, and
that further study may provide evidence for its existence in other species.